Speed-change device



T. R. STURGEON.

SPEED CHANGE DEVICE.

APPLICATION FILED QCT- 2, I919.

1,374,614. w .Patnted Apr. 12, 1921.

I 5 2 $HEET$-S|1EET I- ?l 5 QttoamugS T. R. STU'RGEON. SPEED CHANGE DEVICE. LICATION FILED OCT. 2 I9 Patented Apr. 12, 1921.

SHEETSSHEET 2.

THOMAS E. STURGEON, OF NEW YORK, N. Y.

SPEED-CHANGE DEVICE.

To all whom it may concern:

Be it known-that I, THOMAS B. STURGEON, a subject of the King of Great Britain, and a resident of the city, county, and State of New York, (whose post-ofiice address is Chas. Butters & Co, Ltd, 90 West street,-

New York city,)- have invented certain new and useful Improvements in Speed-Change Devices, of which the/following is a specification.

My invention relates to "a speed reduction device and has special application to diifer ential arrangements'used for the purpose of transmittin rotary motion from one member to anot er.

It was anobject in designing apparatus embodying my invention to simplify the same, to remove all toothed gearing therefrom, to eliminate friction as much as possible, to provide an arrangement whereby the driving and driven members are concentric, at the same time producing a structure which is simple and compact, and balanced so as to eliminate vibration.

The following is a description of an embodiment of my invention and will be better understood by referring to the accompanying drawings forming a part thereof, and in which- Figure 1 is a sectional elevation of one form of the apparatus;

Fig. 2 is a section on Fig. 3 is a section on line 3-3 of Fig-1;

Fig. 4 is a detail of the eccentric;

Fig. 5 is a sectional elevation of another embodiment of my invention;

Figs. 6, 7 and 8 are details of the couphng means;

Fig. '9 is a diagram; and

Fig. 10 shows another embodiment of the invention.

Referring to Fig. 1, the apparatus consists of a bed plate 1; carrying a bearing block 2 for the driven shaft 3. Mounted on the bed late 1 is a member 4, which supports a caring 5 forthe driving shaft 6. The member 4' has an upright part 7;, Mounted also on the bed plate 1 is an up 'ri ht member 8 parallel w1th the, member 7. v o'unted. bet'ween "the vmembers .7 and"8 are "a pluralityof .rollers' 9, 10,11 and 12, there ""berng'founin this particular -structure. Each of therollers-has a shaft'journaled one end Specification of Letters Patent.

line 2-2 of Fig. 1;

Patented Apr. 12, 1921.

' Application filed October 2, 1919. Serial No. 327,991.

in the member 7 and the other end in the member 8. These four rollers are equally spaced on their circular center line, and in this structure have centers 90 degrees apart and are concentric with the shaft 6.

Mounted on the shaft 6 and rigid therewith is an eccentric 13 and mounted on the eccentric 13 is a cam 14s.. Also mounted on the shaft 6 is a counterbalance 13 for the purpose of balancing said shaft. One end of the cam 14, has three. projections 15, 16 and 17 and the other end has two projections 18 and 19. The contacting surfaces of the cam are in the form of substantial arcs of circles.

Mounted parallel to the members 7 and 8 are two members 20. and 21, which members 20 and 21, however, are free-from the bed plate 1, and as will appear later, revolve around concentric with the shafts 3 and 6.

Mounted between the members 20 and 21 are three rollers 22, 23 and 24, each having a shaft journaled one end in the member 20 and the other end in the member 21. The member 20 has an opening in the center thereof sufficient to allow for the movement of the cam 14. The member 8 also has such anopening. The member '21- is rigidly fastened to thedriven shaft 3 and drives the same. It will be noted that the shaft 6 extends into a central opening in the end of the'shaft 3, which opening forms a bearin for the shaft 6. The cam 14 is so mounte on the eccentric 13 that it may rotate with respect thereto.

The operation of the device above dein the members-7 and 8 relative to the bed 'plateg-itherefore, as the projections 15, 16,

and 17 on one end of the cam 14 engage the rollers, the cam is given a rotative movement around the eccentric 13, and in fact rotates in a direction opposite the rotation of th Shaft 6. The cam 14 being rigid through- Ratio:X(Y1) to 1 Where Y equals the number of rollers in the fixed set and X equals the number of rollers in the movable set. It is also true that when X is equal to or less than Y1, the drive is positive, that is to say, the shaft 6 and 3 rotate in the same direction but at different speeds, while X is greater than Y-l, the drive is negative, that is to say, the shaft 3 rotates in a direction opposite to that of shaft 6' and at a speed dependent upon the. number of rollers employed. The 7 number of projections on the end of the 25 cam 14 is always one less than the number of rollers engaged by that end.

' From the foregoing it will be apparent that by varying the number of rollers of the two sets, certain ratios can be obtained, that is to say, certain ratios give'a positive drive and certain other ratios give a negative drive.

While the frame containing'the rollers .9-12 has been described as being fixed to the bed plate 1, it is obvious'that this frame might be arranged so that it might revolve and its speed of-revolution controlled thereby varying the speed of shaft 3 or stopping it altogether while shaft '6 continues to revolve; or the power may be applied to this frame and theshafts 3 and 6 rotated at the same or different speeds as in the well known automobile differential.

same as that of Fig. 1 except the second set of rollers, to wit the rollers 22, 23 and 24 have been omitted together with the members. 20 and 21. The power is transmitted 'in that arrangement from the shaft -6 to the shaft 3 through the cam .14, rollers 912 asin Fig. 1, and then through an Oldham coupling, so that the speed of the shaft 3 is the same as the speed of rotation of the cam 14, which speed is determined by the number of rollers corresponding to those numbered 912; that is to say, in the example shown, there being four rollers, the speed of rotation of the cam 14 would be three to one in a direction oppositeto the rotation of the shaft 6, and therefore, would be a negative drive. The coupling shown in detail in Figs. 6, 7 and 8 comprises a member 25 rigidly connected with the cam -14,'in fact} integral therewith. There is also a member 5 26 whichhas thereon a feather or projec The modification shown in Fig. 5 is the By the modification of the invention shown in Fig. 5 any desired ratio consisting of a whole number from 2 to 1 upward may be obtained. It is noted also that by this modification nothing but a negative drive can be produced. The ratio of the speed re-, duction would be as. the number of rollers minus one is to one. I

The following is the correct method of arriving at the proportions of the engaging surfaces so as to give to the driving member a constant angular velocity.

In Fig. 9 the diameter of circle B is equal to the diameter of the circular path followed by the eccentric 13, which gives to the cam 14 the same bodily circular travel. The diameter of circle A is equal to the diameter of circle B multiplied by the number of rollers in the set considered. Points E equally div'ided circle A into parts equal in number to the number of rollers in the set. When circle B is midway between two of these points E, an are which will pass through two points E and will also touch circle B at point C (point C bisecting the arc) will define the radius FE which will: be equal toFC. A circleJ struck from the same center as circle A and passing through point F represents the rol er circle. Fig. 9 is drawn for four rollers and points F represent their centers.

The radius of the rollers G. may be any- ,thing less than the radius FE which is suitin manufacture.

The portion H of the cam, which touches the roller G will closel approximate to an arc of 'a circle and wilf be of'such'form as will give a uniform angular'velocity to the drive member. The number of parts H will be one less than the number of rollers in the set considered. g y

Fig. 'lQshows an arrangement in which ,both frames carrying the rollers or' "other bearingsurfaws 9, 10, 11, 12, 22, 23 and 24, are free from the bed plate 1." One of these frames, as 7-8, may be driven by motor 32 through a belt 33 or other suitable means' The two frames 7-8 and ..20-21 are mounted on a single shaft 34 and are free to rotate thereon. This shaft 34 is provided with an eccentric correspondin to the e0 centric 13 of Fig. 1 and alsowlth the cam 14, as in the other figures. The frame 21 drives a pulley 35 by means of a belt 36 or other suitable means. By using my invention in the embodiment of Fig. 10 the motor 32 drives a shaft 37 at a speed change in accordance with the following formula:

Y X-l Rat1o= XT t0 1,

Y=number of rollers in driving set and X number' of rollers in driven set, and the drive is always positive. Inthe apparatus shown in the drawings, if the frame 7-8 is driven, the speed ratio between the frames 78 and 20-21 would be eight-ninths.

From the foregoing it will be seen that the embodiments of my invention are ex.- tremely simple, are rugged and compact, and that friction is reduced to a. minimum.

It is obvious that if found desirable, ballbearings may be provided at any desired point such as, for instance, between the eccentric 13 and cam 14.

It is obvious also that instead of rollers 9-12 and 2224, fixed surfaces of the proper configuration might be used without departing from the spirit of my invention, although I prefer to use rollers on account of the fact that they tend to eliminate friction between the bearing surfaces.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a speed change device, the combination of a driving member, a double cam having projections in the form of substantial arcs of circles on each end thereof and operated by said member, a plurality of sta-- tionary rollers engaged by one end of said cam and a plurality of rollers on a driven member operated by the other end of said N cam.

2. In a speed change device, the combination of a driving member, a cam having uniform projections in the form of substantial arcs of circles thereon operated thereby, stationary rollers engaged by one end of said cam and a different number of movable rollers engaged by the other end of said cam.

3. In a speed change device, the combination of a driving and a concentric driven member, a set of rollers connected with the driven member, a fixed set of rollers and means including a cam having a different numberof proj cations in the form of substantial arcs of circles on the ends thereof engaging said sets of rollers for driving said driven member at a different speed from that of said driving member.

4. In a speed change device, the combination of a driving member, a double ended cam loosely mounted on said membeiyprojections in the form of substantial arcs of circles on each end of said cam, a fixed member engaged by one end of said cam whereby the speed of the cam is reduced relatively to that of the driving member, a member engaged by the other end of the cam whereby it is driven at a reduced speed relatively to i the cam.

5. In a speed change device, the combination of a driving and a concentric driven member, speed reducing means connecting said members and comprising a double ended cam operated by said driving member and vrotatable relative thereto, a set of rollers engaged by one end of said cam and controlling the rotation thereof, and a second set of rollers engaged by said cam and rotated thereby, the contacting surfaces ofthe cam being substantially arcs of circles.

6. In a speed change device, the combination of a driving member and a concentric driven member, speed reducing means connecting said members comprising a fixed and a movable set of rollers and a rotating double ended cam engaging said rollers and operated by said driving member, the contacting surfaces of the cam being substantially arcs of circles.

7.. In a speed change device, the combination of a .driving member and a driven member, a double ended cam, means on the driving member for operating the cam, a fixed frame, means in said frame engaging with said cam to give said cam a rotative movementrelative to said driving member, and a rotatable frame connected to said driven member and operated by said cam, the contacting surfaces of the cam being substantially arcs of circles.

8. In a speed change device, the combination of a driving member, a double cam operated by said member, a plurality of rollers engaged by one end of said cam and a plurality of rollers on a driven member operated by the other end of said cam, the contacting surfaces of the cam being substantially arcs of circles.

9. In'a speed change device, the combination of a driving member, a cam having uniform projections thereon operated thereby, rollers engaged by one end of said cam and a different number of rollers engaged by the other end of said cam, the contacting surfaces of the cam being substantially arcs 'of circles.

10. In a speed change device, the combination of a double cam having a plurality of projections. 'on each end, a frame having a plurality of circular surfaces therein for engagement with the projections on one end of-said cam, a second frame with a plurality of circular surfaces therein for engagement with a bearing supporting one end of said driving member, a cam eccentrieally mounted and rotatable on said drivlng member, each end of said cam consistmg of an inlot tegral symmetrical plurality of curves substantially the same as arcs of circles and differing in number one end from the other, a fixed set of rollers engaged by one end of said cam and controlling the rotation thereof, a movable set of rollers on said driven member engaged by the other end of said cam, the number of rollers in each set being one more than the number of curves on said cam engaged thereby, said sets of rollers and driving and driven members being concentric.

12. In a speed change device, the combination of a driving member, a concentric driven member with a bearing supporting one end em-p14 of said driving member, a cam eccentrically mounted and rotatable on said'driving member, said cam having integral with it a symmetrical plurality of curves substantially the same as arcs of circles, a fixed set of rollers concentric with said driving member and numbering one more than the curvesflon said cam and controllingthe rotation thereof,

means for transmittlng the rotation of said eocentrically mounted cam to said concentric driven member.

In testimony whereof, I have signed my name to this specification.-

THOMAS R. STURGEON. 

